Node.js Developers: Your crypto Module Already Does JWT

The key insight: You don't need external JWT libraries cluttering your node_modules when Node.js ships with everything required to create secure, signed tokens.

I've watched too many Node.js projects accumulate JWT dependencies that add hundreds of megabytes to builds, introduce supply-chain vulnerabilities, and provide features most applications never use. Meanwhile, the node:crypto module sits there, battle-tested and maintained by the Node.js core team, capable of handling the cryptographic heavy lifting that JWT libraries were designed for.

Why JWT Libraries Are Often Overkill

Most JWT libraries bring significant baggage. The popular jsonwebtoken package pulls in multiple dependencies, each representing potential security vectors. For a typical API that just needs to sign user session data, you're trading simplicity for features you'll likely never touch.

The math is simple: JWTs are just header.payload.signature where the signature proves the token wasn't tampered with. Node's crypto module handles HMAC-SHA256 (symmetric) and ECDSA/RSA (asymmetric) signing out of the box - the same algorithms JWT libraries use under the hood.

Building Your Own Lightweight Token System

Here's a practical implementation using only Node.js built-ins:

1import crypto from 'node:crypto';
2
3class LightweightJWT {
4  constructor(secret) {
5    this.secret = secret;
6  }
7
8  // Base64URL encoding (JWT standard)

Usage is straightforward:

1const jwt = new LightweightJWT('your-secret-key');
2
3// Sign a token
4const token = jwt.sign({ userId: 123, role: 'admin' }, '2h');
5
6// Verify and decode
7try {
8  const decoded = jwt.verify(token);
9  console.log(decoded); // { userId: 123, role: 'admin', iat: ..., exp: ... }
10} catch (error) {
11  console.log('Invalid token:', error.message);
12}

The Security Benefits You Gain

This approach actually improves security in several ways:

• Reduced attack surface: Zero external dependencies means no supply-chain vulnerabilities from JWT library ecosystems
• Timing attack protection: Using crypto.timingSafeEqual() for signature comparison prevents timing-based attacks
• Full control: You decide exactly what goes into headers and payloads, no hidden library behaviors
• Audit simplicity: 50 lines of code vs. thousands in external libraries

When to Stick with Libraries

This lightweight approach works best for:

• Simple authentication scenarios
• Microservices with basic token needs
• Projects prioritizing minimal dependencies
• Teams comfortable with crypto fundamentals

Stick with established libraries when you need:

• Complex key rotation via JWKS endpoints
• Multiple algorithm support (ES256, RS256, etc.)
• Advanced features like refresh token flows
• Compliance requirements demanding certified implementations

Production Considerations

For production deployments, enhance the basic implementation:

• Key management: Rotate secrets regularly, never hardcode them
• Algorithm flexibility: Support ES256 for better performance with smaller keys
• Revocation strategy: Maintain a blocklist for compromised tokens
• Monitoring: Log all verification failures for security analysis

1// Enhanced verification with logging
2verify(token) {
3  try {
4    return this.baseVerify(token);
5  } catch (error) {
6    // Log security events
7    console.warn('Token verification failed:', {
8      error: error.message,
9      timestamp: new Date().toISOString(),
10      tokenPrefix: token.substring(0, 20) + '...'
11    });
12    throw error;
13  }
14}

Why This Matters

Every external dependency is a bet on another team's security practices, maintenance commitment, and architectural decisions. When Node.js provides the primitives you need, using them directly gives you control, reduces complexity, and eliminates a class of vulnerabilities entirely.

The node:crypto module isn't going anywhere - it's maintained by the same team ensuring Node.js security. Your lightweight JWT implementation will be more predictable, debuggable, and secure than depending on the JavaScript package ecosystem's latest JWT flavor.

Next step: Audit your current JWT usage. If you're only signing simple payloads for API authentication, try replacing that heavyweight library with a custom implementation. Your node_modules folder - and your security team - will thank you.